Enzymatic peptide fragments, mapping

Mapping Carbohydrate Heterogeneity in Enzymatic Peptide Fragments. 

Peptide-mass fingerprinting. In this approach, also known as peptide-mass mapping, the protein is first subjected to enzymatic digestion to generate a set of peptides that are unique to this protein (Section 8.4) [20,42-47]. The molecular mass of each fragment is determined accurately (within 0.5 Da) using MALDI-MS or ESI-MS. Correlation of these masses with the theoretical peptide... 

In Chapter 4 we described a number of examples using plasma desorption mass spectrometry to map enzymatic digests. However, continuing an earlier example from this chapter, plasma desorption mass spectrometric analysis of amyloid peptides (PAi 4o and PAi 2) digested with pepsin resulted in peaks at m/z 561.1,613.1, 746.1, 1492.2, 1999.2, 2199.9, and 2315.2 that could be assigned to the peptide fragments ... 

Tryptic Maps of Relaxin and Relaxin B-chain. Digestion of the A-chain of human relaxin with trypsin can theoretically result in the release of five fragments that of the B-chain in the release of six fragments as illustrated in Table II. A typical tryptic map of relaxin B-chain is shown in Figure 2. The peptide was reduced and carboxymethylated with iodoacetic acid before enzymatic digestion. The peptide assignments were made after analysis of the peaks by amino acid hydrolysis for amino acid composition and confirmed by fast atom bombardment mass spectrometry (FAB-MS) as shown in Table IH... 

Peptide mapping, after selective enzymatically or chemically induced fragmentation of the product into peptides, followed by chromatographic separation and identification by sequencing techniques, UV-absorption, mass spectrometry or other alternatives, serves as a combination technique by which various types of biopharmaceuticals may be thoroughly characterized. An indication of genetic stabihty can be demonstrated by comparison with reference materials, as incorrect amino acids resulting from mutation or mistranslation of the cDNA sequence can be determined. 

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